Probability of a team to score in sports

Hi All,

A basic (hopefully) conditional probability question, but I can't get my head around.

I want to calculate the probability based on past data that a team will score a goal, say in soccer (football to the Europeans, of which I am one :) ). I imagine this depends not only on Team A's scoring record, but also Team B's likelihood to concede.


Say Team A, in their last 100 games has scored 1 goal 50 times and 0 goals 50 times. Therefore there is a probability of 0.5 that they will score a goal.

However, Team B, in their last 100 games have conceded a goal in only 25 of their games and conceded no goals in 75. I.e. probability to concede a goal is 0.25.

For Team A to score a goal, it has to score one, but Team B must concede one. So is this a simple multiplication of the probabilities, 0.5*0.25?

However there is clearly some correlation between the two events, which leads me to think it's not as straightforward as this. Can someone comment on what the probability would be?